The present invention relates to an interface unit for transmitting control signals from a controller to an apparatus to be controlled. In particular, the invention relates to a universal interface unit for connecting a synchronizer to any one of a plurality of different types of recorders.
In the recording of information on magnetic storage tapes, it is often necessary to record separate pieces of the information on different tapes with the use of different recorders. For example, video information might be recorded on one tape while accompanying audio information is recorded on a second tape. During playback of these tapes, it is necessary to insure that they are in synchronism so that the information is presented in the same fashion as it was recorded. Thus, if the video recorder is rewound to replay a particular segment of the information, the audio recorder must also be rewound so that the appropriate accompanying sound is also replayed.
The synchronism of the tapes is carried out with the use of a time code that is simultaneously recorded onto all of the tapes along with the information of interest. During playback, the time codes on the tapes are monitored and the operation of the recorders are controlled so that the time codes are in synchronism. In the preceding example, the time code from the video tape recorder is monitored as a master time code, and the speed and direction of the audio tape recorder are controlled by a synchronizer unit so that the time code on the audio tape is the same as the master code.
A practical problem encountered in the control of one or more recorders by a synchronizer unit is occassioned by the different types of control signals required by different recorders. For example, a recorder produced by one manufacturer may require a particular D.C. level to be maintained to operate the recorder in a fast forward mode, whereas a different manufacturer's recorder may require a pulse to begin the fast forward operation and a subsequent pulse to halt it.
In the past, the need for different types of control signals for different recorders was met by the use of a dedicated interface that was custom designed for a particular recorder and the synchronizer. Each different recorder required its own interface to provide the appropriate control signals. An interface is a relatively expensive piece of equipment and, in an environment where a number of recorders are to be operated in synchronism, the costs for required interface units alone can be substantial.
This problem is not unique to recorders. It is a real concern in a variety of situations in which control or information signals generated in one piece of equipment must be appropriately modified or conditioned in an interface unit before they can be applied to another peice of equipment.